The sky signal is a composite of ground-emission spillover, atmospheric emission, and cosmic signal attenuated by the atmospheric absorption
and is beyond the scope of this discussion (see [1]} for more information).
If two measurements of the sky are performed along one of the switching procedures described in Sect. 1, we can compute their
difference to cancel all unwanted signals and retrieve only the cosmic signal of interest (\(T_{\mathrm {sky}}\)  is hereafter referred to with the
more commonly used \(T_{\mathrm {a}}\)  or antenna temperature, and similarly \(V_{\mathrm {sky}}\)  becomes \(V_{\mathrm {a}}\) ):
\(\Delta T_{\mathrm {a}} = T_{\mathrm {a,ON}}-T_{\mathrm {a,OFF}} = g\times (V_{\mathrm {a,ON}}-V_{\mathrm {a,OFF}}),\) 
